Preheat oven to 400ºF. Bring 2 cups water to a boil. Stir in cereal, cinnamon and salt. Simmer, stirring, until tender, about 10 minutes. Remove from heat.
Slice 2 bananas; arrange in a 9-inch pie plate. Toss nuts with 1 Tbsp. syrup. Stir milk, vanilla and remaining syrup into cereal; spread over bananas. Top with nuts.
Bake until browned, 20 to 25 minutes. Let stand 5 minutes. Slice remaining banana; place on top. Serve.